Punching apparatus



D .2s,1944. v s. s. STINE HAL 2,365,977

PUNCHING APPARATUS .File'd Feb. 13, 1943 FTQB INVENTORS Sam/e1. $.Srms nuo EMIBVIYETT H. BESWICK.

ORNEY UNITED STATES Patented Dec. 26, 1944 PUNCHING APPARATUS Samuel S. Stine, Lansdowne, and Emmett H. Beswick, Essington, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 13, 1943, Serial No. 475,720

6 Claims. (Cl. 16429) This invention relates to metal stamping, more particularly to the punching of openings having relatively wide body portions tapering to relatively thin tail portions in strips or pieces-of metal, and has for an object to provide improved apparatus for thispurpose.

Another object of the invention is to provide an improved design of punch and die resulting in decreased breakage of the punch.

In the manufacture of turbine diaphragms, nozzle blocks and similar structures, it has been found desirable to mount a plurality of vane members in spaced circumferential relation, the vanes extending radially from a central axis and with the ends of the vanes received in openings formed in radially-spaced inner and outer bands or rings. These vane members are generally of airfoil or thin tailed section and the punching of openings in the inner and outer rings'to closely receive the terminal portions of these vane members has presented a difficult problem to turbine manufacturers.

The principal problem lies in the fact that the thin, tail-like portion of the vane section is of such thinness that it has been found impossible to punch an opening having such a narrow dimension Without breaking the corresponding portion of the punch. This problem is responsible for the general rule that the width of any thin, tail-like portion that can be punched, can be no less than the thickness of the material in which the opening is made. For example, if the material of the ring or trip to be punched is of an inch in thickness, then the width of tail portion of the opening can be no less than of an inch, and if the thickness of the ring is /4 of an inch, then the "width of the tail portion can be no less than A,, of an inch.

As a result of this limitation, the turbine industry has heretofore found it necessary to punch the tail portion of vane openings of greater width than that desired and then to perform added operations, involving increased expense, to elim-' inate the extra clearance thereby provided between the walls of the opening andthe'edges of the vane members inserted therein. United States Patents Nos. 1,932,278 and 2,110,679 are tively thin, tail-like portions of a width materially less than the thickness of the material being punched may be punched to the exact size desired.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a perspective view of a portion of a diaphragm ring or nozzle block for use in e1asticfluid using apparatus and involving punching operations producing the problem herein solved;

Fig. 2 is a side elevational view of a punch and die constructed in accordance with the present invention; and,

Fig. 3 is a sectional view taken along the line III-III of Fig. 2, looking in the direction indicated by the arrows.

Referring now to the drawing more in detail, there is shown, at I0 (Fig. 1), a portion of a turbine diaphragm comprising an inner ring H and an outer ring I2 having openings l3 punched therein, the openings being of a shape and size to closely receive the terminal portions of the vane members I4, the spaced vane members providing therebetween and in cooperation with the spaced inner and outer rings II and I2, passages 15 for flow of expansible fluid such as steam, gas,

etc.

In Figs. 2 and 3 there is illustrated a punch and die combination designed for punching the openings l3 to the exact size required to closely receive the terminal portions of the vanes I4.

illustrative of efforts to meet this problem. It

The punch unit It is comprised by a central portion 19 having a shank 21 by which the punch unit may be secured in a suitable power-press in a well-known manner, the body portion I9 having a depending punch element 20 of the configuration shown in Fig. 3. The punch element comprises, in section, a relatively thick body portion 22 merging into a thin tail portion 23.

The die 25 is provided with an opening 26 therethrough, of a shape and size to receive the punch element 20 during normal punching operations. There is provided between the punch and die the customary clearanceA which, for the punching of openings for the purpose above mentioned, would be in the neighborhood of .005. In addition to this clearance, there is provided an extra clearance B at each side of the thin tail portion of the opening for a distance X therealong, this extra clearance varying from .005 to .025 of an inch and the distance X varying from A to of an inch. It should be noted that this clearance B is in addition to the normal clearance A. Also, there is provided an end clearance C varying from .030 to .090 of an inch.

As a result of the provision of these additional clearances about the thin, tail-like portion of the punch, it is possible to punch such openings down to as thin a section as of an inch or less through material of A of an inch thickness or greater.

While applicants cannot be certain as to the change which is produced by provision of these clearances, as regards the action of the metal upon the punch, it is believed that the added clearance provides space for flow of metal which, without the provision of such clearance, binds and grips the thin portion of the punch, thereby breaking the latter.

Throughout the specification and claims, the term vane includes also blades, partitions, buckets, and any similar structure cooperating with other parts to provide elastic-fluid passages.

While the invention has been shown in but one form, it will be'obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. In apparatus for punching openings to receive and space vanes to form elastic-fluid flow passages for elastic-fluid handling apparatus, which vanes are thickened at their inlet edges and taper in the direction of flow to provide rel a tively thin tail portions; a punch of the shape and size .of the openings, and a die having an opening of approximately the shape of the punch and adapted to receive the latter, said die opening providing usual clearances about the thickened portion of the punch and materially greater clearances about the thin portion thereof.

2. Structure as specified in claim 1, wherein the tail portion of the openingin the die extends beyond the corresponding portion of the punch a distance within the range of .030 to .090 of an inch.

3. Apparatus for use in forming openings in strips of metal for reception of vane members of approximately the same size as the openings, which vane members in cross section have a thick body portion and a thin tail portion; said apparatus comprising a punch of substantially the shape and size of the opening to be punched and a die to cooperate therewith, the opening in said die having the last A to of an inch of its thin tail portion relieved at both sides an amount ranging from .005 to .025 of an inch above normal punch clearance.

4. Structure as specified in claim 3, wherein the thin tail portion of the die opening extends beyond the corresponding portion of the punch a distance of from .030 to .090 of an inch.

5. In apparatus for punching an opening having a wide body portion tapering to a relatively thin tail portion; a punch of the shape and size of the opening, and a die having an opening of approximately the shape of the punch and adapted to receive the latter, said die opening providing the usual clearances about the wide portion of the punch and materially greater clearances about the thin portion thereof.

6. Apparatus for punching an opening which is wide at one end and tapered therefrom to the other end to provide a relatively thin tail portion; said apparatus comprising a punch of substantially the shape and size of the opening to be punched and a die to cooperate therewith, the opening in said die having the last A to A, of an inch of its thin tail portion relieved at both sides an amount ranging from .005 to .025 of an inch above normal punch clearance and said thin tail portion of the die opening extending beyond the corresponding portion of the punch a distance of from .030 to .090 of an inch.

SAMUEL S. STINE. EMMETT H. BESWICK. 

